Subspace combination of multisensor output signals

Method and system for recognizing the presence of a reference signal having M components. A signal s(t) is received that may contain a reference signal s(t;ref). An M×M covariance matrix of the M components of the received signal is formed, and M eigenvector solutions V=Vj and associated eigenvalue solutions &lgr;=&lgr;j (j=1, 2, . . . , M) of the matrix relation R·V=&lgr; V are determined. A subspace S′ of the space spanned, spanned by a selected subset of the vectors Vj′ (j′=1, . . . , N(s)) is formed, with N(s) a selected number that is ≦M. Product signals s(t)·Vj′(t) are formed and integrated over a selected time interval, t0≦t′≦t, to form estimation signals xj′(t) (j′=1, . . . , N(s)). The estimation signal xj′(t) and the reference signal s(t;ref) are used to determine a weighting coefficient wj′(t) (j′=1, . . . , N(s)), using a selected weighting criterion, and a sum signal of products of the weighting coefficients and the eigenvectors Vj′(t) is formed, as an estimate of the reference signal contribution to the received signal.